Different position of deposition matrix has a significant impact on the morphology of tungsten tube.

In the end position near the gas outlet, the temperature in temperature region and in deposition temperature is relatively close, but due to the influence of the early deposition reaction, the concentration of WF₆ and H₂ is lowered, and the concentration of HF is increasing, therefore, the speed of tungsten atoms reduction slow down; the crystal grains in temperature region are much finer than in deposition organizations; the thickness of tungsten tube near the gas outlet end is significantly thinner.

Near the gas inlet end position, due to the impact of the inlet gas, the deposition temperature of this place is relatively low, so the columnar crystal of deposited layer microstructure is much smaller in this position; the deposition growth rate is relatively slow.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Nowadays, tungsten oxide (WO_X) electrochromic is the most widely studied. Electrochromic WO_X film is reversed from a bleached state (colorless) to a colored state (dark-blue) to produce tungsten bronze (MαWO_X) by intercalating both ions and electrons according to the intercalation reaction:  WO_X+αM++αe-←→MαWO_X. However, electrochromic WO_X films have poor chemical stability in an acidic electrolyte solution (i.e., a protonic H⁺ ion ^– containing electrolyte) during electrolyte cycling due to the film’s dissolution in the H2SO4 electrolytes solution, therefore, the non-protonic lithium-containing electrolytes are generally used to assure the reversible Li+ intercalation into and deinteralation out from tungsten oxide films. To enhance the lithium eletrochromic properties of WO_X, several dopants such as Au crystals, TiO_X, MoO_x, FeO_X and carbon nanotubes have been added into WO_X films.

After adding dopants it can enhance tungsten oxide films’ lithium electrochromic properties which are under an atmosphere pressing plasma jet. 


Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Fine tungsten powder used more widely, it also makes the study of ultrafine tungsten powder is increasing. Currently the producing method of ultrafine tungsten powder has three main research directions: First, to improve the blue tungsten process. Second, the introduction of new reduction methods, such as hydrogen halide reduction and the third is the use of laser and other new fluidized technology. The study found that using violet tungsten oxide to producing fine particles of tungsten powder is good than using blue tungsten oxide so the producing fine particles of tungsten powder the violet tungsten as material is more popular than blue tungsten oxide. But violet tungsten powder particle sizes also will influent tungsten powder size and properties. Fine violet tungsten powder can produce good properties fine particles so to produce fine particles violet tungsten oxide has a certain significance and role for fine tungsten powder. Producing process as follows:
1. The amount of APT loaded boa then push into hot zone of reduction furnace, while feeding a certain proportion of mixed gas which is hydrogen and water vapor, heated to a predetermined temperature to cool for a while after being room temperature draw a charge
2. In the heating, keeping, cooling process, the gas flow rate remains constant.
3. Using WLP202 type fsss analyzer to analysis raw material and product and the phase of the product analysis by the x-ray diffraction.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Nano tungsten powder is widely used in modern industry and science area, so good performance nano tungsten powder can improve application in the field of modern industry and science which has great significance. But good properties nano tungsten powder producing requirements is quite high. The violet tungsten oxide (VTO) has different properties with other tungsten oxides. It is the most suitable material for produce nano powder, so using VTO as material producing nano tungsten powder not only the tungsten powder has good performance and the process is relatively simple. But in order to producing good properties tungsten oxide in addition to control the raw martial but also need to control the production process which is temperature, push boat speed and the amount of hydrogen, only in gentle heating process, moderate reaction, smooth gas migration so can effectively control the water vapor to escape which is an important factor for producing good properties nano tungsten powder.

By controlling the raw materials and process conditions the nano tungsten powder has high purity and crystallinit as well as has stable properties and loose structure. What’s more the appearance of it is sphere and distribution uniform which has large specific surface area, pore structure simple.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Violet tungsten oxide (VTO) restore to tungsten powder in the first and second redox reactions the particle size of these two reduction has not big different.

Continue to analyze the third redox reaction found the third time tungsten trioxide restore to tungsten powder and the specific surface area of it is 1.082 m² • g^-1 in the third time reaction which is the 6.56 times to second reduction tungsten powder’s specific surface area. Apparently,   third reduction tungsten powder particle size is very small, and most concentrated in the 0.21-1.05um, but there is significant agglomeration, so that the measured particle size is agglomeration but not tungsten powder. According oxidation - reduction mechanism shows that the majority of the oxide reduction process is carried out simultaneously, but some tungsten oxide first reaction and others after reaction then the after reaction tungsten powder will cover in the first reaction tungsten powder so the tungsten powder particle size will group up, so that the tungsten powder particle size distribution is relatively concentrated and uniform.

VTO after third times reduction and second time oxidation can produce submicron tungsten powder particle size between 0.21-1.05um and specific surface area is 1.082 m² • g^-1 which has not coarse particle. 

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

After analyzing tungsten powder which restore from violet tungsten oxide for first time researcher found tungsten powder particle size are smaller and more uniform, but has reunion phenomenon.

Then the researcher analysis the second redox reaction found tungsten trioxide restore to tungsten powder in hydrogen and the specific surface area of tungsten powder is 0.165m² • g^-1 which is the1.71 times to first reduction tungsten powder’s specific surface area. From this data analysis the researchers found comparison the first time and the second time reaction of tungsten powder particle size they didn’t have large different. The second reduction tungsten oxide particle size is mainly between 4.24 and 11.11um, centralized distribution and uniform.

The tungsten powder in the air second oxidize to tungsten trioxide and the specific surface area of it is 0.719 m² • g^-1, is the 4.96 times to first oxidized tungsten trioxide’s specific surface area which is more finer than first time but the distribution is very scattered and not concentrated area. This is mainly because the tungsten trioxide has significant agglomeration, the particle size which measuring is agglomeration not the tungsten trioxide particles.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Because violet tungsten oxide (VTO) producing process and process parameters are simple as well as equipment are easy to control and many advantages so many manufactures are like to use VTO to producing tungsten powder. VTO cycle reduction method can producing excellent performance submicron or micro tungsten powder particles, to further understand tungsten powder in the reactions process which is used cycle reduction method will conducive to the future development and maturity of this method.

After studies, VTO in first hydrogen reduced to tungsten powder and the specific surface area of tungsten oxide is 0.141m² • g^-1 and particle size mainly between 4.72-12.13um. Compared with the original VTO particle size distribution, after first reduction the particle of VTO is significantly thinner, but still existing coarse particles. The tungsten powder in the air oxidation to tungsten trioxide for the first the specific surface area of it is 0.145m² • g^-1, which is 1.13 times of VTO. It can be seen, the first time oxidized to tungsten trioxide the particle are smaller than VTO particle size which is more uniform distribution, but still significant reunion.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Fine and uniformity tungsten powder are key point for producing carbide, and micron and submicron tungsten carbide powder is useful to producing carbide. According to the relevant academic report found that single tungsten oxide can produce submicron or micron tungsten powder. Using violet tungsten oxide (VTO) producing fine tungsten oxide not only the process of it is simple as well as process parameters are easy to control and also equipment are not complex etc. Producing process as follows:
1. VTO were first reduction in hydrogen, along a first temperature of 640 ℃, the second temperature of 760 ℃, third temperature of 860 ℃, when the temperature reaches 860 ℃ heat preservation for 20min.
2. in the air at 500 ℃ making tungsten powder to oxidation with slowly heated for the first time, then heat preservation for 10min.
3. Replace the first step and second to continuous cycle reduction reaction.
4. Using alcohol on the analytical results above steps were dispersed pattern, then using BT-9600 laser particle size analyzer and JXA-840A electron probe scanner to analysis particle size and morphology of samples.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Experimental material: high-purity hydrogen, high purity argon gas and high-purity tungsten hexafluoride and deposition matrix: copper tube.

Experimental procedure:

Decontaminating, acetone washing and drying the surface of deposition matrix, which would be placed in the reaction chamber then.

To avoid the explosion due to hydrogen mixed with air, argon should be purged into the reaction chamber and all the pipelines to empty the air. After emptying air, open the hydrogen flow needle valve, pass over the hydrogen and then light the exhaust gas discharged, then close the valve;

Heating the deposition matrix by current to make it achieve the required deposition temperature;

After mixing the WF₆ and H₂ according to a certain proportion, passing them through the reaction chamber through the flow control device;

WF₆ and H₂ react chemically on the surface of deposition matrix, to obtain deposition layer of refractory metal;

After a certain reaction time, turn off the heating power and reactive gas control valve, so the reaction chamber will be cooling;

Removing the sample after the temperature drop to below 100 ℃, and obtaining tungsten tube by means of cutting, and the removal of the deposition matrix.

By changing the deposition temperature and gas flow rate to get tungsten tube in different processes, and then test its properties.

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Experimental materials and reagents are as follows:

H₂: High Purity(99.999％),it is reduction gas;

WF₆: High Purity(99.9％),it is reactant gas;

Ar: High purity(99.999％), it is used in the reaction system for evacuating air;

Deposition Substrate: copper (there are different diameters: 6mm, 10mm, 16mm, and 35mm);

Tungsten tube is processed by CVD (Chemical Vapor Deposition) method.

Under the following conditions: the deposition temperature is the same (600 ℃), and the deposition matrix diameters (6mm, 10mm, 16mm, 35mm) is different. The morphology of tungsten tube obtained by the aforementioned condition is fine columnar crystals and its growth direction is almost identical to brass radial.

By comparing the microscopic morphology of tungsten tube obtained under the above conditions, what is found that the parameters of tungsten tube in the subsequent depositing process can be ignored, that is to say, you can ignore the impact of the deposition matrix diameter on tungsten tube matrix microstructure morphology.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn